Instruments for HF surgical treatment of tissue are well-known in principle. The problem in this case is frequently undesirable side-effects which can result due to the current flow through the patient's tissue, particularly in the relevant operating region. These undesirable side-effects occur particularly during large-area, superficial procedures such as argon plasma coagulation (APC) or spray coagulation. The high voltages used there, which may be up to 4500 V, can cause malfunctions in electronic peripheral devices due to electromagnetic fields in the operating environment. Among other things, they may have adverse effects on patient monitoring, such as on the ECG. During minimally invasive procedures, it is also necessary to use an endoscopic or laparoscopic camera, the image of which can be adversely affected by the high voltage and the electromagnetic fields this generates as a result. It is therefore necessary to use highly insulating materials to shield the appropriate devices in order to prevent the associated interference.
Carbonization effects of the treated tissue and neuromuscular stimulations which are induced by the HF current are another disadvantage of conventional HF surgical procedures. Finally, another disadvantage of conventional HF surgical instruments is the necessity of carrying out an instrument change for different HF surgical treatment steps such as cutting, injecting or coagulating tissue which hampers the surgical procedure. It should also be possible to carry out thermal tissue treatment by means of HF surgical coagulation with maximum tissue conservation. This includes reducing the coagulation depth while simultaneously increasing the surface extension of the coagulation region.
An object of embodiments of the present invention is therefore to create a multifunctional instrument which requires no instrument change for different treatment steps and which moreover prevents side-effects such as interference with peripheral devices, carbonization effects and neuromuscular stimulations.